[Fixes #107] Discount code 'lookup'

Author: tareqtms

README.md

@@ -290,6 +290,7 @@ Some resources are available directly, some resources are only available through
 - CustomerSavedSearch -> [Customer](https://help.shopify.com/api/reference/customer/)
 - [DraftOrder](https://help.shopify.com/api/reference/draftorder)
 - [Discount](https://help.shopify.com/api/reference/discount) _(Shopify Plus Only)_
+- [DiscountCode](https://help.shopify.com/en/api/reference/discounts/discountcode)
 - [Event](https://help.shopify.com/api/reference/event/)
 - [FulfillmentService](https://help.shopify.com/api/reference/fulfillmentservice)
 - [GiftCard](https://help.shopify.com/api/reference/gift_card) _(Shopify Plus Only)_
@@ -385,9 +386,9 @@ The custom methods are specific to some resources which may not be available for
     Perform bulk operations against a number of addresses
 
 - DraftOrder ->
-    - [send_invoice()]()
+    - [send_invoice($data)]()
     Send the invoice for a DraftOrder
-    - [complete()]()
+    - [complete($data)]()
     Complete a DraftOrder
 
 - Discount ->
@@ -396,6 +397,10 @@ The custom methods are specific to some resources which may not be available for
     - [disable()]()
     Disable a discount
 
+- DiscountCode ->
+    - [lookup($data)]()
+    Retrieves the location of a discount code.    
+    
 - Fulfillment ->
     - [complete()](https://help.shopify.com/api/reference/fulfillment#complete)
     Complete a fulfillment

lib/DiscountCode.php

@@ -10,10 +10,25 @@
 namespace PHPShopify;
 
 
+/**
+ * --------------------------------------------------------------------------
+ * DiscountCode -> Custom actions
+ * --------------------------------------------------------------------------
+ * @method array lookup()       Retrieves the location of a discount code.
+ *
+ */
+
 class DiscountCode extends ShopifyResource
 {
     /**
      * @inheritDoc
      */
     protected $resourceKey = 'discount_code';
+
+    /**
+     * @inheritDoc
+     */
+    protected $customGetActions = array(
+        'lookup',
+    );
 }

lib/ShopifySDK.php

@@ -78,6 +78,7 @@
  * @property-read Customer $Customer
  * @property-read CustomerSavedSearch $CustomerSavedSearch
  * @property-read Discount $Discount
+ * @property-read DiscountCode $DiscountCode
  * @property-read DraftOrder $DraftOrder
  * @property-read PriceRule $PriceRule
  * @property-read Event $Event
@@ -117,6 +118,7 @@
  * @method CustomerSavedSearch CustomerSavedSearch(integer $id = null)
  * @method Discount Discount(integer $id = null)
  * @method DraftOrder DraftOrder(integer $id = null)
+ * @method DiscountCode DiscountCode(integer $id = null)
  * @method PriceRule PriceRule(integer $id = null)
  * @method Event Event(integer $id = null)
  * @method FulfillmentService FulfillmentService(integer $id = null)
@@ -163,6 +165,7 @@ class ShopifySDK
         'Customer',
         'CustomerSavedSearch',
         'Discount',
+        'DiscountCode',
         'DraftOrder',
         'Event',
         'FulfillmentService',